Rotorcraft Glade Grip

ABSTRACT

A rotorcraft main rotor system, including a yoke, a rotor blade, and a grip assembly attaching the rotor blade to the yoke. The grip assembly includes a grip body formed from a contiguous laminated composite and has a substantially constant thickness, where the grip body has an upper extension, a lower extension and a connecting portion connected between an inboard end of the upper extension and an inboard end of the lower extension. An inside surface of the upper extension faces, and is substantially parallel to, an inside surface of the lower extension, and the upper extension has first features and the lower extension has second features that are aligned with the first features, where the first features and second features each include at least one of an edge contour, attachment holes, or first protective elements.

PRIORITY CLAIM AND CROSS-REFERENCE

This application is a divisional of U.S. patent application Ser. No.16/372,732, filed on Apr. 2, 2019, and entitled “Rotorcraft Blade Grip,”which application is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to a rotorcraft rotor assemblyapparatus, and more specifically to a structural rotorcraft blade gripsystem and method for making the same.

BACKGROUND

Rotorcraft provide lift and thrust by rotating a set of rotor bladesattached to a rotor hub that is driven by a power transmission gearboxthrough a rotor mast. Engines of the rotorcraft turn the rotor mast bydriving a transmission connected to the rotor mast, and turn the rotorblades attached to the rotor mast. On a rotorcraft main rotor, the mainrotor blades may have substantial weight and length, and, when turningat full speed, are subject to significant centrifugal force. The mainrotor blades are attached by main rotor blade grips to a main rotor yokethat is attached to the rotor mast. The main rotor grips securely attachthe main rotor blades to the yoke through a spherical thrust bearingwhich permits each of the main rotor blades to independently flapvertically, rotate on a long axis to provide cyclic and collectivecontrol of the rotorcraft, and move forward or backward within the rotorplane to lead or lag the grip attachment point.

SUMMARY

An embodiment rotorcraft main rotor system includes a yoke, a rotorblade, and a grip assembly attaching the rotor blade to the yoke. Thegrip assembly includes a grip body formed from a contiguous laminatedcomposite and has a substantially constant thickness, where the gripbody has an upper extension, a lower extension and a connecting portionconnected between an inboard end of the upper extension and an inboardend of the lower extension. An inside surface of the upper extensionfaces, and is substantially parallel to, an inside surface of the lowerextension, and the upper extension has first features and the lowerextension has second features that are aligned with the first features,where the first features and second features each include at least oneof an edge contour, attachment holes, or first protective elements.

An embodiment grip assembly, includes a grip body having an upperextension, a lower extension and a connecting portion, where theconnecting portion is disposed between, and connects, an inboard end ofthe upper extension and an inboard end of the lower extension, where thegrip body is formed from a laminated composite extending contiguouslyfrom the upper extension, through the connecting portion, to the lowerextension, where the laminated composite has a plurality of layers, eachlayer of the plurality of layers extending contiguously along a lengthof the upper extension, around the connecting portion, and along alength of the lower extensions, wherein the grip body has a constantthickness along the length of the upper extension, around the connectingportion, and along the length of the lower extension, where an insidesurface of the upper extension faces, and is substantially parallel to,an inside surface of the lower extension, and where an inside surface ofthe connecting portion has a contiguous curvature between the upperextension and lower extension.

An embodiment method includes forming a laminated structure by applyinga plurality of layers of laminating material and a bonding material to amolding fixture, where each layer of the plurality of layers oflaminating material, other than the outermost layers of the plurality oflayers of laminating material, has a different fiber orientation than afiber orientation of at least one immediately adjacent layer of theplurality of layers of laminating material, rolling at least one layerof the plurality of layers of laminating material, vacuum pressing thelaminated structure on the molding fixture, forming a grip blank bysetting the bonding material, where the grip blank includes an uppersheet, a lower sheet and a connecting blank portion, where theconnecting blank portion is disposed between, and connects, the uppersheet and the lower sheet, where the grip blank comprises a laminatedcomposite extending contiguously from the upper sheet, through theconnecting blank portion, to the lower sheet, and where the grip blankhas a constant thickness along a length of the upper sheet, around theconnecting portion, and along a length of the lower sheet. The methodfurther includes removing the grip blank from molding fixture, forming areference feature in the grip blank, mounting the grip blank on atooling fixture, and cutting a grip body from the grip blank withrespect to the reference feature, where the grip body has an upperextension, a lower extension and a connecting portion, wherein theconnecting portion is disposed between, and connects, an inboard end ofthe upper extension and an inboard end of the lower extension, and wherean inside surface of the upper extension faces, and is substantiallyparallel to, an inside surface of the lower extension.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a rotorcraft 101 according to some embodiments;

FIG. 2A illustrates a rotor blade that may be attached to the main rotorsystem 103 according to some embodiments;

FIG. 2B illustrates a detailed view of the root end of a rotor bladeaccording to some embodiments;

FIG. 3 illustrates a main rotor system with a grip assembly andinstalled rotor blade according to some embodiments;

FIG. 4 is a cutaway diagram illustrating features of a main rotor systemaccording to some embodiments;

FIG. 5 illustrates a grip assembly for a rotorcraft according to someembodiments;

FIGS. 6a through 6e illustrate fabrication of a grip body according tosome embodiments; and

FIG. 7 is a flow chart illustrating a method for fabricating the gripassemblies according to some embodiments.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Illustrative embodiments of the system and method of the presentdisclosure are described below. In the interest of clarity, all featuresof an actual implementation may not be described in this specification.It will of course be appreciated that in the development of any suchactual embodiment, numerous implementation-specific decisions may bemade to achieve the developer's specific goals, such as compliance withsystem-related and business-related constraints, which will vary fromone implementation to another. Moreover, it should be appreciated thatsuch a development effort might be complex and time-consuming but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure.

Reference may be made herein to the spatial relationships betweenvarious components and to the spatial orientation of various aspects ofcomponents as the devices are depicted in the attached drawings.However, as will be recognized by those skilled in the art after acomplete reading of the present disclosure, the devices, members,apparatuses, etc. described herein may be positioned in any desiredorientation. Thus, the use of terms such as “above,” “below,” “upper,”“lower,” or other like terms to describe a spatial relationship betweenvarious components or to describe the spatial orientation of aspects ofsuch components should be understood to describe a relative relationshipbetween the components or a spatial orientation of aspects of suchcomponents, respectively, as the device described herein may be orientedin any desired direction.

The increasing use of rotorcraft, in particular, for commercial andindustrial applications, has led to the development of larger morecomplex rotorcraft. However, as rotorcraft become larger and morecomplex, the differences between flying rotorcraft and fixed wingaircraft has become more pronounced. Since rotorcraft use one or moremain rotors to simultaneously provide lift, control attitude, controlaltitude, and provide lateral or positional movement, different flightparameters and controls are tightly coupled to each other, as theaerodynamic characteristics of the main rotors affect each control andmovement axis. For example, the flight characteristics of a rotorcraftat cruising speed or high speed may be significantly different than theflight characteristics at hover or at relatively low speeds.Additionally, different flight control inputs for different axes on themain rotor, such as cyclic inputs or collective inputs, affect otherflight controls or flight characteristics of the rotorcraft. Forexample, pitching the nose of a rotorcraft forward to increase forwardspeed will generally cause the rotorcraft to lose altitude. In such asituation, the collective may be increased to maintain level flight, butthe increase in collective requires increased power at the main rotorwhich, in turn, requires additional anti-torque force from the tailrotor. This is in contrast to fixed wing systems where the controlinputs are less closely tied to each other and flight characteristics indifferent speed regimes are more closely related to each other.

Recently, fly-by-wire (FBW) systems have been introduced in rotorcraftto assist pilots in stably flying the rotorcraft and to reduce workloadon the pilots. The FBW system may provide different controlcharacteristics or responses for cyclic, pedal or collective controlinput in the different flight regimes, and may provide stabilityassistance or enhancement by decoupling physical flight characteristicsso that a pilot is relieved from needing to compensate for some flightcommands issued to the rotorcraft. FBW systems may be implemented in oneor more flight control computers (FCCs) disposed between the pilotcontrols and flight control systems, providing corrections to flightcontrols that assist in operating the rotorcraft more efficiently orthat put the rotorcraft into a stable flight mode while still allowingthe pilot to override the FBW control inputs. The FBW systems in arotorcraft may, for example, automatically adjust power output by theengine to match a collective control input, apply collective or powercorrection during a cyclic control input, provide automation of one ormore flight control procedures provide for default or suggested controlpositioning, or the like.

FIG. 1 illustrates a rotorcraft 101 according to some embodiments. Therotorcraft 101 has a main rotor system 103, which includes a pluralityof rotor blades 105. The pitch of each rotor blade 105 may be controlledby a swashplate 107 in order to selectively control the attitude,altitude and movement of the rotorcraft 101. The swashplate 107 may beused to collectively and/or cyclically change the pitch of the rotorblades 105. The rotorcraft 101 also has an anti-torque system, which mayinclude a tail rotor 109, no-tail-rotor (NOTAR), or dual main rotorsystem. In rotorcraft with a tail rotor 109, the pitch of each tailrotor blade 111 is collectively changed in order to vary thrust of theanti-torque system, providing directional control of the rotorcraft 101.

Power is supplied to the main rotor system 103 and the anti-torquesystem by engines 115. There may be one or more engines 115. The outputof the engine 115 is provided to a driveshaft 117, which is mechanicallyand operatively coupled to the main rotor system 103 and the anti-torquesystem through a main rotor transmission 119 and a tail rotortransmission 121, respectively.

The rotorcraft 101 further includes a fuselage 125 and tail section 123.The tail section 123 may have other flight control devices such ashorizontal or vertical stabilizers, rudder, elevators, or other controlor stabilizing surfaces that are used to control or stabilize flight ofthe rotorcraft 101. The fuselage includes a cockpit 127, which includesdisplays, controls, and instruments. It should be appreciated that eventhough rotorcraft 101 is depicted as having certain features, therotorcraft may have a variety of implementation-specific configurations.

Collective pilot flight controls allow a pilot to control collectiveconfigurations, such as collective blade pitch, to rotor blades 105.Collective configurations of rotor blades 105 may change overall liftproduced by rotor blades 105. For increasing or decreasing overall liftin rotor blades 105, the angle of attack for all rotor blades 105 may becollectively altered by equal amounts at the same time, resulting inascent, descent, acceleration, or deceleration. Alteration of collectiveconfiguration of rotor blades 105 may be accomplished by input from acollective control assembly (not illustrated).

FIG. 2A illustrates a rotor blade 105 that may be attached to the mainrotor system 103 according to some embodiments. The rotor blade 105 hasa leading edge 201, a trailing edge 203, a root end 205, and a tip end207. It should be appreciated that rotor blade 105 may be configured orotherwise suitably adapted to take on a variety of configurations. Forexample, rotor blade 105 can have a degree of built-in twist betweenroot end 205 and tip end 207. In another embodiment, rotor blade 105 canhave an anhedral tip, or any other desired aerodynamic profile.

FIG. 2B illustrates a detailed view of the root end 205 of a rotor blade105 according to some embodiments. Mounting holes 209, 211, and 213, aredisposed in the rotor blade near the root end 205 and provide openingsfor fasteners that may be used to attach the rotor blade 105 to astructure of the main rotor system 103. The mounting holes 209, 211 and213 may be configured to accept fasteners such as bolts, pins, clips,screws, rivets, or the like. The mounting holes 209, 211, and 213 may,in some embodiments, include bushings, or the like, located therein as abearing surface for the shanks of the fasteners. While three mountingholes 209, 211 and 213 are shown, other embodiments may contain moremounting holes or fewer mounting holes.

Rotor blade 105 may also include a forward taper 215 and an aft taper217 that each taper toward a centerline axis of rotor blade 105 untiljoining at a rounded portion 219. Rounded portion 219 can have a radiusas a function of a desired edge distance from for example, mounting hole209.

FIG. 3 illustrates a main rotor system 103 with a grip assembly 305 andinstalled rotor blade 105 according to some embodiments. The main rotorsystem 103 includes a yoke 301 coupled to a mast 303. Each rotor blade105 is coupled to yoke 301 by a grip assembly 305. The grip assembly 305is U-shaped or C-shaped, with an upper extension 315 extending over atop side of the yoke 301 away from the yoke 301, and with a lowerextension 317 extending below a bottom side of the yoke 301 away fromthe yoke 301. An inboard portion of each grip assembly 305 is securedwithin an opening of yoke 301 by a centrifugal force (CF) bearing 313.Each rotor blade 105 is attached to the outboard portion of gripassembly 305 by fasteners 311, such as bolts, pins, clamps, of the like.A pitch horn 309 has portions that extend between rotor blade 105, andupper extension 315 and lower extension 317 of grip assembly 305.Dampers 307 are attached between yoke 301 and a damper attachmentportion 319 of the pitch horns 309.

FIG. 4 is a cutaway diagram illustrating features of main rotor system103 according to some embodiments. The grip assembly 305 has aconnecting portion 401 disposed between, and connecting, the upperextension 315 and the lower extension 317, forming a channel. In someembodiments, the upper extension 315, connecting portion 401, and lowerextension 317 form a single contiguous member. The CF bearing 313 isdisposed within the channel of the grip assembly 305, and may, in someembodiments, bear the grip assembly 305 and rotor blade 105 against theyoke 301. The CF bearing 313 permits the rotor blade 105 to pivot andflex with respect to the yoke 301 without requiring a complex hingesystem. In some embodiments, the connecting portion 401 is contiguouslycurved between the upper extension 315 and the lower extension 317, withthe curvature of the connecting portion facing, or curving towards, theupper extension 315 and lower extension 317. The curvature of the insideradius of the connecting portion 401 may be configured to accept the CFbearing 313, so that an outside surface of the CF bearing 313complements, and seats against, the inside face of the connectingportion 401.

In some embodiments, the pitch horn 309 includes an upper flange 405 aand lower flange 405 b. The rotor blade 105 may be disposed between theupper flange 405 a and the lower flange 405 b. The rotor blade 105 andpitch horn 309 are disposed in the channel of the grip assembly 305between grip assembly 305 upper extension 315 and lower extension 317,and are connected to an outboard portion of the grip assembly 305.

FIG. 5 illustrates a grip assembly 305 for a rotorcraft according tosome embodiments. The grip assembly 305 has a grip body 501 comprisingthe upper extension 315, the lower extension 317, and the connectingportion 401. In some embodiments, the grip body 501 is formed from acontiguous laminated composite and has a substantially contact thicknessthrough the upper extension 315, lower extension 317, and connectingportion 401. The laminated composite may have a plurality of layers,where each laminate layer of the plurality of layers is a carbon fibertape, carbon fiber cloth, fiberglass tape or cloth, foam layer, spacerlayer, or the like. In some embodiments, each laminate layer of theplurality of layers is a unidirectional carbon fiber tape, and eachlaminate layer of the plurality of layers may have a differentorientation of fiber compared to one or both of the adjacent layers. Insome embodiments, each layer of laminating material, other than theoutermost layers of laminating material, has a different fiberorientation than a fiber orientation of at least one immediatelyadjacent layer of the plurality of layers of laminating material. Eachlaminate layer may be bonded by a resin material such as a thermosettingepoxy or polymer, catalyzed epoxy, ultraviolet (UV) cured epoxy,thermoplastic laminating material, or other adhesive or laminatingmaterial. Each laminate layer of the plurality of layers extends alongthe length of the upper extension 315, around the connecting portion401, and along the length of the lower extension 317, and in someembodiments, the number of layers is the same in the upper extension,the connecting portion 401 and the lower extension 317, resulting theconstant thickness throughout the grip body 501.

The inside surfaces of the upper extension 315 and lower extension 317face each other, and, in some embodiments, are substantially parallel toeach other. In some embodiments, the upper extension 315 and lowerextension 317 have corresponding features, where the upper extension 315has first features and the lower extension 317 have second features thatcorrespond to the first features. Corresponding features are featuresthat are aligned with matching or associated features on an opposingextension, and may include grip body edge contour, tooling datum holes,attachment holes, protective elements, or the like. For example, theupper extension 315 may have first attachment holes 503 a and the lowerextension 317 may have second attachment holes 503 b that are alignedrespectively with the first attachment holes 503 a. Thus, pins, bolts,clips or the like that may extend through the first attachment holes 503a and through corresponding ones of the second attachment holes 503 b.In another example, the edges of the upper extension 315 may besubstantially aligned with the edged of the lower extension 317.

In some embodiments, the grip body 501 is wider at an outboard end thanat an inboard end, with the width of the grip body 501 at the inboardend nearest the connecting portion 401 being narrower than at theoutboard end to reduce the weight of the grip body 501. Additionally, insome embodiments, the grip body 501 has lobes 529 formed by the contourof the edges of the upper extension 315 and the lower extension 317. Thelobes 529 in grip body 501 may correspond to, follow, or otherwise beassociated with, the radius of the outer attachment holes 503 a. Coves527 are disposed on the edge of upper extension 315 between the outerfirst attachment holes 503 a and on the edge of the lower extension 317between the outer second attachment holes 503 b. The coves 527 mayreduce the weight of the grip assembly 305 by reducing the amount ofmaterial forming the grip body 501. In some embodiments, the grip body501 may also have additional lightening features for reducing the weightof the grip body 501, such as recesses, lightening holes, or the like.

The grip assembly 305 may, in some embodiments, further have one or moreprotective features that protect the grip body 501 from adverseconditions such as abrasion, pressure, debris, contamination, and thelike. The protective features may include bushings, bearings, protectivepads, protective surfaces, coatings, shields, coverings, and the like.In some embodiments, attachment holes 503 a and 503 b have bushings 511,or the like, as a bearing surface or protective surface for fasteners311, such as bolts pins, or other attachment structures used to securethe rotor blade in the grip assembly 305. The bushings 511 may be formedfrom bronze, aluminum, steel, titanium, nylon, fiberglass, carbon fiber,or another wear-resistant material, and may extend substantially throughthe respective attachment hole 503 a and 503 b. In some embodiments, thebushings 511 have a flange that prevents the bushings from migrating outof the attachment holes 503 a and 503 b. The flanges may be disposed onthe inside of the grip body 501, and may have a thickness that spacesthe upper extension 315 and the lower extension 317 apart from anystructures that are attached between the upper extension 315 and lowerextension 317. Additionally, protective pads 515 may affixed around thefirst attachment holes 503 a and second attachment holes 503 b toprotect the grip body 501 from abrasion due to movement, installation orremoval of fasteners. In some embodiments, the protective pads 515 aredisposed on the outside face of the upper extension 315 or lowerextension 317 opposite the flange of the bushings 511. In otherembodiments, the protective pads 515 may be disposed on the inside facesof the upper extension 315 and lower extension 317, with the bushingsarranged so that the bushing flanges are at the outside faces of theupper extension 315 and lower extension 317. In yet another embodiment,the protective pads 515 are part of the bushing 511, with the bushinghaving flanges at each end. In such an embodiment each bushing 511 maybe a two piece structure, with different pieces of a bushing 511 beinginserted from opposite ends of an attachment hole 503 a and 503 b.

The grip body 501 may also have one or more accessory holes in additionto the attachment holes 503 a and 503 b. For example, the grip body 501may have pitch horn attachment holes 509 in the upper extension 315 andthe lower extension 317. The pitch horn attachment holes 509 may havebushings 513 or the like as a bearing surface for shanks of pitch hornattachment fasteners, and the bushings 513 may have flanges that aredisposed on the inside faces of the upper extension 315 and lowerextension 317, and may have shanks or bodies that extend substantiallythrough the pitch horn attachment holes 509.

A protective pad 517 may be affixed to the outside surfaces of the upperextension 315 and the lower extension 317. The protective pad 517 may bedispose around the pitch horn attachment hole 509. The grip body 501 mayalso have machining features or reference features such as tooling datumholes 519 in the upper extension 315 and in the lower extension 317. Thetooling datum holes 519 may be reference structures used as a referenceduring machining of the grip body 501

In some embodiments, the protective pads 515 and 517 may be pads orstructures that are bonded to the surface of the grip body 501 after thegrip body 501 is molded and machined. This permits multiple grip bodies501 to be laid up in a single blank and machined from the single blank,reducing the number of blanks needed to produce a set number of gripbodies 501. In some embodiments, the protective pads 515 and 517 arefiberglass pads that may be formed separately from the grip body 501,and then adhered or otherwise attached to surfaces of the grip body 510,and in other embodiments, the protective pads 515 and 517 may be formedin place on the grip body 501. In other embodiments, the protective pads515 and 517 may be another sacrificial or protective material such asrubber sheet, nylon, a polytetrafluoroethylene (PTFE) material, apolyester fiber or cloth or elastomeric material, a polyoxymethylene(POM) or acetal material, high density polyethylene (HDPE) or anotherpolymer, or a metallic material such a bronze, titanium, steel,aluminum, or the like.

In some embodiments, the protective features may also include protectivesurfaces 523 and 525 disposed in the surfaces and edges of the grip body501. The protective surfaces 523 and 525 may be formed from a flexiblematerial to permit the material to conform to the curved or contouredsurface portion of the grip body. For example, the protective surfaces523 and 525 may be formed from rubber sheet, or a polyester fibermaterial bonded to the grip body 515. The protective surfaces 523 and525 may include an interior protective surface 523 disposed on theinside surface of connecting portion 401 where the CF bearing 313 mateswith the connecting portion 401. Edge protective surface 525 may also bea polyester fiber material bonded to edge surface of connecting portion401 where a CF bearing 313 clamp engages with connecting portion 401. Insome embodiments, the interior protective surface 523 may be formed froma different material than the edge protective surfaces 525, for example,with the interior protective surface 523 formed from rubber sheet, andthe edge protective surfaces 525 formed from polyester fiber material.Additionally, in some embodiments, the protective surfaces 523 and 525may be another low friction or wear resistant material or coating suchas fiberglass, carbon fiber, nylon, a PTFE material, a POM or acetalmaterial, HDPE, or another polymer, or a metallic material such abronze, titanium, steel, aluminum, or the like.

In some embodiments, the connecting member 401 may have a chamfer 531 orother feature that relieves the corner or edge of the connecting memberto reduce stress on the CF bearing. In some embodiments, the interiorprotective surface 523 may be separate from the edge protective surface525, and spaced apart from the edge protective surface 525 by thechamfer. In such an embodiment, the chamfer 531 may be free of theprotective surfaces 523 and 525. In other embodiments, the interiorprotective surface 523 may be contiguous with the edge protectivesurface 525, extending from the interior surface of the grip body 315,over the chamfer or corner of the grip body 315 to the edge surface ofthe grip body 315.

FIGS. 6a through 6e illustrate fabrication of a grip body according tosome embodiments. FIG. 6a illustrates application of an initial layer oflaminating material 603 to a molding fixture 601. The molding fixture601 may have a finished edge 611 which, in some embodiments, is curvedor otherwise contoured to provide a desired shape for the interiorsurface of the connecting member of a grip body.

The laminating material 603 may be carbon fiber tape, carbon fibercloth, fiberglass, or similar laminating material. In some embodiments,the laminating material 603 may be a prepreg material, where thelaminating material 603 is pre-impregnated with a bonding material. Inembodiments where prepreg material is used, applying the laminatingmaterial 603 includes the application of the laminate cloth and bondingmaterial at the same time, avoiding additional steps of applying bondingmaterial separately. However, in other embodiments where the laminatingmaterial is non-prepreg material, a bonding material may be applied tothe initial laminating material layer 603, after the laminating material603 is set in place, and may be rolled on, or otherwise spread toimpregnate the initial layer of laminating material 603 with the bondingmaterial. In some embodiments, the bonding material, whether applied aspart of the application of the prepreg laminating material, or appliedseparately, may be a resin material such as a thermosetting epoxy orother laminating adhesive that remains workable while additional layersof laminating material are applied. The initial layer of laminatingmaterial 603 extends from a first major surface of the molding fixture601, around the finished edge 611, to a second major surface of themolding fixture 601 opposite the first major surface.

FIG. 6b illustrates application of additional layers of laminatingmaterial 605 and 607 to be laminated onto initial layer of laminatingmaterial 603. In some embodiments, laminating material layer 605 isapplied on the initial layer of laminating material 603, with a fiberorientation differing from that of layer 603, and a bonding material maybe applied to saturate the additional layer of laminating material 605.Another additional layer of laminating material 607 may be applied overthe layer of laminating material layer 605, and additional bondingmaterial may be applied for non-prepreg laminating material. The bondingmaterial may be rolled, sprayed, spread, or otherwise worked into thelayers of laminating material 603, 605 and 607. In some embodimentswhere the layers of laminating material 603, 605 and 607 are non-prepregmaterial, a roller is used to spread the bonding material and work thebonding material into the layers of laminating material 603, 605, and607. In some embodiments where the layers of laminating material 603,605 and 607 are prepreg material, the layers may be rolled or otherwisepressed to adhere the layers together and ensure a complete bond. Aroller further permits an operator to press the layers of laminatingmaterial 603, 605 and 607 together, eliminating air pockets, wrinklesand other imperfections. Additionally, using a bonding material with acontrollable curing cycle permits multiple layer of laminating material603, 065 and 607 to be applied quickly without waiting for the bondingmaterial to cure.

A grip blank for one or more grip bodies may be formed by applyingadditional layers of laminating material fillers such as foam or nomexlayers, or the like, and by application of additional bonding material,as disclosed above. The additional layers of laminating material may beapplied so that some adjacent layers of laminating material havedifferent fiber or weave orientations to increase the strength andmaterial stability of the finished grip bodies. In some embodiments,each additional layer of the lamination material may extend from thefirst major surface of the molding fixture 601, around the finished edge611, to the second major face of the molding fixture 601 so that theresulting stack of lamination material layers has a substantiallyconstant thickness along the length and width of the grip blank,permitting multiple grip bodies to be cut from a single grip blank.However, in other embodiments, partial layers of laminating material,reinforcement material, braces, or the like, may be included in thestack of laminating material layers to strengthen or customize specificportions of the resulting parts. Layers of laminating material may beapplied until a desired thickness of lamination is achieved. In someembodiments, the stack of laminating material layers and bondingmaterial are vacuum pressed, such as by vacuum bagging, to compress thelayers of laminating material laminated on the molding fixture, and thebonding material may then be cured. In some embodiments, the bondingmaterial is a thermosetting epoxy, and may be cured in an oven, viainfrared heating, or by another heating process, while the layers oflaminating material are being vacuum bagged.

FIG. 6c illustrates grip blank 609 on the molding fixture 601 accordingto some embodiments. After the bonding material is cured, any vacuumbagging is removed, and the resulting structure is a grip blank 609. Thegrip blank 609 is then removed from the molding fixture for furtherprocessing. In some embodiments, the major faces of the molding fixture601 may have a slight taper to facilitate removal of the grip blank 609.

FIG. 6d shows the grip blank 609 after removal from molding fixture 601according to some embodiments. The grip blank 609 has an upper sheet613, a lower sheet 615, and a connecting blank portion 617 disposedbetween the upper sheet 613 and lower sheet 615. In some embodiments,the inside surface of the connecting blank portion 617 has a contiguouscurvature between the upper sheet 613 and lower sheet 615. The radius ofthe inside surface of the connecting portion 617 corresponds to theoutside radius of finished edge 611 of the molding fixture 601, andcorresponds to an outside radius of a CF bearing of main rotor system.In other embodiments, the outside radius of molding fixture 601 finishededge 611 may correspond to a yoke portion, or other retention mechanismfor a main rotor system.

In some embodiments, the grip blank 609 has the same number of laminatedlayers in the upper sheet 613, the lower sheet 615 and the connectingblank portion 617, and, as a result, has a substantially constantthickness along the length of the upper sheet 613, around the connectingblank portion 607, and along the length of the lower sheet 615.

FIG. 6e illustrates machining of the grip blank 609 according to someembodiments. The grip blank 609 is mounted on a tooling fixture 619, andone or more grip bodies 501 are machined from the grip blank 609. Insome embodiments, multiple grip bodies 501 are cut from the grip blank609 using a milling machine 621, high pressure abrasive liquid or waterjet system, laser cutting tool, or another cutting or milling system.

In some embodiments, the milling machine 621 may form one or moretooling datum holes that are used as reference points for subsequentmilling operations. In other embodiments, tooling datum holes may beformed in the grip blank 609 prior to the grip blank 609 being mountedon the tooling fixture 619 so that the milling machine 621 moves inreference to the tooling fixture 619 and tooling datum holes.

In some embodiments, the tooling fixture 619 may be rotated or moved sothat the milling machine 621 cuts separately though opposite sides ofthe grip clamp. In other embodiments, the milling machine 621 cuts theupper sheet 613 and lower sheet 615 at the same time, resulting in theedge features and holes of the upper sheet 613 and lower sheet 615corresponding.

FIG. 7 is a flow chart illustrating a method 701 for fabricating thegrip assemblies according to some embodiments. In block 703, a firstlayer of laminating material and bonding material is applied to themolding fixture. In some embodiments, the laminating material is prepregmaterial having a bonding material disposed in, or impregnated into, thelaminating material prior to use. In other embodiments, a bondingmaterial is applied to the initial layer of laminating material on themolding fixture, for example, where a plain or non-prepreg laminatingmaterial is used. In block 707, a next or subsequent layer of laminatingmaterial is applied over a previously applied layer of laminatingmaterial. In some embodiments where the non-prepreg laminating materialis used, additional bonding material may be applied over the additionalor next layer of laminating material. In block 709, the next orsubsequent layer of laminating material is rolled onto the previouslayers so that the bonding material causes the laminating material tobond to the previous laminating material layers. In some embodiments,each layer of laminating material is applied so that it has a differentorientation of fiber compared to at least one adjacent layer. Thus, twoimmediately adjacent first layers of laminating material may have thesame fiber orientation, but additional second layers that areimmediately adjacent to the first layers may have different fiberorientations. In some embodiments, each layer of laminating material,other than the outermost layers of laminating material, has a differentfiber orientation than a fiber orientation of at least one immediatelyadjacent layer of the plurality of layers of laminating material.

Blocks 707 through 709 are repeated until the desired thickness oflamination has been achieved. In block 711, the stack of laminatingmaterial and bonding material on the molding fixture vacuum bagged orotherwise pressed together to remove air bubbles and press the layers oflaminating material together and squeeze out any excess bondingmaterial, and assure consistent lamination. In block 713, the bondingmaterial is cured. Setting the bonding material will depend on thebonding material used. For example, a structure using a thermoset epoxybonding material may be cured in an oven at a specific temperature for aspecific time period, while a UV cured polymer may be exposed to UVradiation to cure the bonding material. After the bonding material isset or cured, the grip blank is complete and may be removed from themolding fixture in block 715.

In block 717, one or more reference features, such as tooling datumholes, are formed in the grip blank, and may be used as machiningreference points for subsequent machining. In block 719, the grip blankis mounted onto a tooling fixture. In block 721, one or more holes, suchas attachment holes and the like, may be milled, cut, drilled, orotherwise formed forming attachment holes. In block 723, one or moregrip bodies may be cut from the grip blank by milling or by anothercutting, milling, or machining process. In block 725, additionalfinishing, or milling, such as machining edges may be performed. Inblock 727, protective features may be applied to the grip body. In someembodiments, the protective features include protective pads, bushings,protective surfaces or the like. In some embodiments, the protectivepads or protective surfaces may be formed separately from the grip bodyand mounted or attached to surfaces edges of the grip body afterformation of the respective protective feature, or may be formed inplace.

While the method 701 illustrates the reference holes being formed priorto the grip blank being mounted on the tooling fixture, and the holesbeing formed in the grip blank prior to the grip body being cut from theblank, it should be understood that the method 701 is not limited to anyparticular order of steps. For example, the reference holes may beformed in the grip blank after the grip blank is mounted to the toolingfixture, the holes may be formed before the grip blank is mounted to thetooling fixture, before the references holes are formed, or after thegrip body is cut from the grip blank.

An embodiment rotorcraft main rotor system includes a yoke, a rotorblade, and a grip assembly attaching the rotor blade to the yoke. Thegrip assembly includes a grip body formed from a contiguous laminatedcomposite and has a substantially constant thickness, where the gripbody has an upper extension, a lower extension and a connecting portionconnected between an inboard end of the upper extension and an inboardend of the lower extension. An inside surface of the upper extensionfaces, and is substantially parallel to, an inside surface of the lowerextension, and the upper extension has first features and the lowerextension has second features that are aligned with the first features,where the first features and second features each include at least oneof an edge contour, attachment holes, or first protective elements.

In some embodiments, the first features and the second features includeattachment holes, and the grip assembly further includes bushingsdisposed in the attachment holes. In some embodiments, an outboard endof upper extension and an outboard end of the lower extension lowerextension have each lobes corresponding to one or more of the attachmentholes, and the outboard end of upper extension and the outboard end ofthe lower extension each have each a cove between the respective lobes.In some embodiments, the first features and the second features includethe attachment holes, the first features and the second features furtherinclude the first protective elements, the first protective elementsinclude a first protective pad affixed on an outside surface of theupper extension around the attachment holes of the upper extension, andthe first protective elements further include a second protective padaffixed on an outside surface of the lower extension around theattachment holes of the lower extension. In some embodiments, theconnecting portion has a second protective element, and the secondprotective element includes a polyester fiber material affixed to aninside surface of connecting portion and an edge surface of connectingportion. In some embodiments, the system further includes a pitch hornextending between the inside surface of the upper extension and therotor blade and further extending between the inside surface of thelower extension and the rotor blade. In some embodiments, an insideradius of the connecting portion has a substantially contiguous curveextending from the upper extension to the lower extension.

An embodiment grip assembly, includes a grip body having an upperextension, a lower extension and a connecting portion, where theconnecting portion is disposed between, and connects, an inboard end ofthe upper extension and an inboard end of the lower extension, where thegrip body is formed from a laminated composite extending contiguouslyfrom the upper extension, through the connecting portion, to the lowerextension, where the laminated composite has a plurality of layers, eachlayer of the plurality of layers extending contiguously along a lengthof the upper extension, around the connecting portion, and along alength of the lower extensions, wherein the grip body has a constantthickness along the length of the upper extension, around the connectingportion, and along the length of the lower extension, where an insidesurface of the upper extension faces, and is substantially parallel to,an inside surface of the lower extension, and where an inside surface ofthe connecting portion has a contiguous curvature between the upperextension and lower extension.

In some embodiments, each layer of the plurality of layers has adifferent fiber orientation than a fiber orientation of an immediatelyadjacent layer of the plurality of layers. In some embodiments, theupper extension has first attachment holes and the lower extension hassecond attachment holes that correspond to, and are aligned with, thefirst attachment holes. In some embodiments, the grip body furtherincludes bushings disposed in the first attachment holes and the secondattachment holes, a first protective pad disposed on an outside surfaceof the upper extension around a first one of the first attachment holes,and a second protective pad disposed on an outside surface of the lowerextension around a second one of the second attachment holes. In someembodiments, the first protective pad extends contiguously aroundadditional ones of the first attachment holes, and the second protectivepad extends contiguously around additional ones of the second attachmentholes. In some embodiments, an outboard end of the upper extension iswider than the inboard end of the upper extension, an outboard end ofthe lower extension is wider than the inboard end of the lowerextension, an outboard edge of the outboard end of the upper extensionhas first lobes corresponding to two or more of the first attachmentholes and at least one first cove disposed between the first lobes, andan outboard edge of the outboard end of the lower extension has secondlobes corresponding to two or more of the second attachment holes and atleast one second cove disposed between the second lobes. In someembodiments, the grip assembly further includes a first polyester fibermaterial disposed on the inside surface of the connecting portion, and asecond polyester fiber material disposed on an edge surface of theconnecting portion.

An embodiment method includes forming a laminated structure by applyinga plurality of layers of laminating material and a bonding material to amolding fixture, where each layer of the plurality of layers oflaminating material, other than the outermost layers of the plurality oflayers of laminating material, has a different fiber orientation than afiber orientation of at least one immediately adjacent layer of theplurality of layers of laminating material, rolling at least one layerof the plurality of layers of laminating material, vacuum pressing thelaminated structure on the molding fixture, forming a grip blank bysetting the bonding material, where the grip blank includes an uppersheet, a lower sheet and a connecting blank portion, where theconnecting blank portion is disposed between, and connects, the uppersheet and the lower sheet, where the grip blank comprises a laminatedcomposite extending contiguously from the upper sheet, through theconnecting blank portion, to the lower sheet, and where the grip blankhas a constant thickness along a length of the upper sheet, around theconnecting portion, and along a length of the lower sheet. The methodfurther includes removing the grip blank from molding fixture, forming areference feature in the grip blank, mounting the grip blank on atooling fixture, and cutting a grip body from the grip blank withrespect to the reference feature, where the grip body has an upperextension, a lower extension and a connecting portion, wherein theconnecting portion is disposed between, and connects, an inboard end ofthe upper extension and an inboard end of the lower extension, and wherean inside surface of the upper extension faces, and is substantiallyparallel to, an inside surface of the lower extension.

In some embodiments, forming the grip blank includes forming the gripblank with the constant thickness along the length of the upper sheet,around the connecting portion, and along a length of the lower sheet,with a constant thickness along the width of the upper sheet, and with aconstant thickness along the width of the lower sheet, and wherein thecutting the grip body from the grip blank includes cutting more than onegrip body from a same grip blank. In some embodiments, after cutting thegrip body from the grip blank, an outboard end of the upper extension iswider than the inboard end of the upper extension, and an outboard endof the lower extension is wider than the inboard end of the lowerextension. In some embodiments, cutting the grip body from the gripblank further includes forming first attachment holes in the upperextension, and forming second attachment holes in the lower extensionthat correspond to, and are aligned with, the first attachment holes. Insome embodiments, the method further includes providing a firstprotective pad on an outside surface of the upper extension around thefirst attachment holes, providing a second protective pad on an outsidesurface of the lower extension around the second attachment holes,inserting first bushings into the first attachment hole and secondbushings into the second attachment holes, and affixing a polyesterfiber material to an inside surface of connecting portion and an edgesurface of the connecting portion. In some embodiments, cutting the gripbody from the grip blank further includes cutting the grip blank so thatan outboard edge of an outboard end of the upper extension has firstlobes corresponding to two or more of the first attachment holes and atleast one first cove disposed between the first lobes, and so that anoutboard edge of an outboard end of the lower extension has second lobescorresponding to two or more of the second attachment holes and at leastone second cove disposed between the second lobes.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

What is claimed is:
 1. A method, comprising: forming a laminatedstructure by applying a plurality of layers of laminating material and abonding material to a molding fixture, wherein each layer of theplurality of layers of laminating material, other than the outermostlayers of the plurality of layers of laminating material, has adifferent fiber orientation than a fiber orientation of at least oneimmediately adjacent layer of the plurality of layers of laminatingmaterial; rolling at least one layer of the plurality of layers oflaminating material; vacuum pressing the laminated structure on themolding fixture; forming a grip blank by setting the bonding material,wherein the grip blank comprises an upper sheet, a lower sheet and aconnecting blank portion, wherein the connecting blank portion isdisposed between, and connects, the upper sheet and the lower sheet,wherein the grip blank comprises a laminated composite extendingcontiguously from the upper sheet, through the connecting blank portion,to the lower sheet, and wherein the grip blank has a constant thicknessalong a length of the upper sheet, around the connecting portion, andalong a length of the lower sheet; removing the grip blank from moldingfixture; forming a reference feature in the grip blank; mounting thegrip blank on a tooling fixture; and cutting a grip body from the gripblank with respect to the reference feature, wherein the grip body hasan upper extension, a lower extension and a connecting portion, whereinthe connecting portion is disposed between, and connects, an inboard endof the upper extension and an inboard end of the lower extension, andwherein an inside surface of the upper extension faces, and issubstantially parallel to, an inside surface of the lower extension. 2.The method of claim 1, wherein forming the grip blank comprises formingthe grip blank with the constant thickness along the length of the uppersheet, around the connecting portion, and along a length of the lowersheet, with a constant thickness along the width of the upper sheet, andwith a constant thickness along the width of the lower sheet; andwherein the cutting the grip body from the grip blank comprises cuttingmore than one grip body from a same grip blank.
 3. The method of claim1, wherein, after cutting the grip body from the grip blank, an outboardend of the upper extension is wider than the inboard end of the upperextension, and an outboard end of the lower extension is wider than theinboard end of the lower extension.
 4. The method of claim 1, whereincutting the grip body from the grip blank further comprises: formingfirst attachment holes in the upper extension; and forming secondattachment holes in the lower extension that correspond to, and arealigned with, the first attachment holes.
 5. The method of claim 4,further comprising: providing a first protective pad on an outsidesurface of the upper extension around the first attachment holes;providing a second protective pad on an outside surface of the lowerextension around the second attachment holes; inserting first bushingsinto the first attachment hole and second bushings into the secondattachment holes; and affixing a polyester fiber material to an insidesurface of connecting portion and an edge surface of the connectingportion.
 6. The method of claim 4, wherein cutting the grip body fromthe grip blank further comprises: cutting the grip blank so that anoutboard edge of an outboard end of the upper extension has first lobescorresponding to two or more of the first attachment holes and at leastone first cove disposed between the first lobes, and so that an outboardedge of an outboard end of the lower extension has second lobescorresponding to two or more of the second attachment holes and at leastone second cove disposed between the second lobes.
 7. A methodcomprising: forming a grip body of a grip assembly from a contiguouslaminated composite such that the grip body has a substantially constantthickness, wherein the grip body is formed with an upper extension, alower extension and a connecting portion connected between an inboardend of the upper extension and an inboard end of the lower extension,wherein an inside surface of the upper extension faces, and issubstantially parallel to, an inside surface of the lower extension, andwherein the grip body is shaped to attach a rotor blade of a rotorcraftto a yoke; providing first features on the upper extension and secondfeatures on the lower extension, wherein the second features that arealigned with the first features, and wherein the first features andsecond features each comprise at least one of an edge contour,attachment holes, or protective pads; and providing protective surfaceson the connecting portion, wherein providing the protective surfacescomprises affixing a first element of the protective surfaces an outersurface of an inward facing portion of the connecting portion, whereinsecond elements of the protective surfaces are spaced apart from thefirst element of the protective surfaces and are affixed to edgesurfaces of the connecting portion.
 8. The method of claim 7, whereinproviding the first features and the second features comprise providingattachment holes; and wherein the method further comprises providingbushings disposed in the attachment holes.
 9. The method of claim 7,wherein forming the grip body comprises: forming one or more lobescorresponding to one or more of the attachment holes in an edge ofoutboard end of the upper extension and in an edge of an outboard end ofthe lower extension; forming a cove in the edge of outboard end of theupper extension between lobes of the upper extension; and forming a covein the edge of the outboard end of the lower extension between lobes ofthe lower extension.
 10. The method of claim 7, wherein providing thefirst features and the second features comprises providing theattachment holes as the first features and the second features, andfurther comprises providing the protective pads as the first featuresand the second features; wherein the protective pads comprise a firstprotective pad affixed on an outside surface of the upper extensionaround the attachment holes of the upper extension; and wherein theprotective pads further comprise a second protective pad affixed on anoutside surface of the lower extension around the attachment holes ofthe lower extension.
 7. method of claim 7, wherein the protectivesurfaces comprise a polyester fiber material.
 12. The method of claim 7,further comprising installing the grip body on the rotorcraft with apitch horn extending between the inside surface of the upper extensionand the rotor blade and further extending between the inside surface ofthe lower extension and the rotor blade.
 13. The method of claim 7,wherein an inside radius of the connecting portion has a substantiallycontiguous curve extending from the upper extension to the lowerextension.
 14. A method, comprising: providing a grip body having anupper extension, a lower extension and a connecting portion, wherein theconnecting portion is disposed between and connects an inboard end ofthe upper extension and an inboard end of the lower extension, andwherein the grip body is formed from a laminated composite extendingcontiguously from the upper extension, through the connecting portion,to the lower extension, wherein the laminated composite has a pluralityof layers, each layer of the plurality of layers extending contiguouslyalong a length of the upper extension, around the connecting portion,and along a length of the lower extensions, wherein the grip body has aconstant thickness along the length of the upper extension, around theconnecting portion, and along the length of the lower extension, whereinan inside surface of the upper extension faces, and is substantiallyparallel to, an inside surface of the lower extension, wherein an inwardfacing portion of the connecting portion has a contiguous curvaturebetween the upper extension and lower extension; and providingprotective surfaces on the connecting portion, and wherein a firstelement of the protective surfaces is affixed to an outer surface of theinward facing portion of the connecting portion, wherein second elementsof the protective surfaces are spaced apart from the first element ofthe protective surfaces and are affixed to edge surfaces of theconnecting portion.
 15. The method of claim 14, wherein each layer ofthe plurality of layers has a different fiber orientation than a fiberorientation of an immediately adjacent layer of the plurality of layers.16. The method of claim 14, further comprising: forming first attachmentholes in the upper extension; and forming second attachment holes in thelower extension, wherein the second attachment holes correspond to, andare aligned with, the first attachment holes.
 17. The method of claim16, further comprising: providing bushings disposed in the firstattachment holes and the second attachment holes; providing a firstprotective pad on an outside surface of the upper extension and around afirst one of the first attachment holes; and providing a secondprotective pad on an outside surface of the lower extension and around asecond one of the second attachment holes.
 18. The method of claim 17,wherein the first protective pad extends contiguously around additionalones of the first attachment holes; and wherein the second protectivepad extends contiguously around additional ones of the second attachmentholes.
 19. The method of claim 16, wherein an outboard end of the upperextension is wider than the inboard end of the upper extension, andwherein an outboard end of the lower extension is wider than the inboardend of the lower extension; and wherein an outboard edge of the outboardend of the upper extension has first lobes corresponding to two or moreof the first attachment holes and at least one first cove disposedbetween the first lobes, and wherein an outboard edge of the outboardend of the lower extension has second lobes corresponding to two or moreof the second attachment holes and at least one second cove disposedbetween the second lobes.
 20. The method of claim 14, furthercomprising: providing a first polyester fiber material disposed on theinside surface of the connecting portion; and providing a secondpolyester fiber material disposed on an edge surface of the connectingportion.